Excellence in Research: Assessing the Control by Multiple Micropredators on Bacterial Communities in Estuarine Environments and Characterization of Prey Lysis Products Resulting fr

卓越的研究：评估多种微捕食者对河口环境中细菌群落的控制以及由此产生的猎物裂解产物的表征

• 批准号: 1948758
• 负责人: Henry Williams
• 金额: $ 92.92万
• 依托单位: Florida Agricultural and Mechanical University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-05-01 至 2025-04-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1948758&HistoricalAwards=false
• 关键词: Excellence; Research; Assessing; Control; Multiple

Microbes are the most abundant organisms on Earth and play an important role as degraders, cycling nutrients in the environment. Too many or too few bacteria may disrupt a sensitive ecological balance and proper functioning of environmental processes such as carbon, nitrogen and phosphorus cycles. The abundance of bacteria populations in any given environment is controlled by various biological, chemical and physical mechanisms. Among the biological agents are microscopic predators, or micropredators, of bacteria. The most studied of these are protists, viruses that infect bacteria, and a group of bacteria collectively known as the Bdellovibrio and like organisms (BALOs). These micropredators prey upon certain bacteria to obtain required nutrients or other cellular material for their replication. In the process, cellular products from the prey bacteria are released into the environment and utilized as nutrients by other microbes. Although the micropredators co-occur, and likely interact, in nature, most experimental studies have investigated their activities individually, rather than collectively. As a result, little is known about their collective role in controlling bacteria populations and the cycling of nutrients. The goal of the proposed research is to address this gap in knowledge by investigating all three as a collective group under simulated natural conditions representing a range of temperature, salinity and abundance of prey. This project is conducted at two Historically Black Universities (HBCUs) with strong records of training and mentoring students and postdocs from underrepresented populations in science. The project benefits up to 100 students by providing unique and meaningful educational and research training experiences at the undergraduate and graduate student levels and for early-career scientist. Specific activities include courses on scientific writing and presenting results at annual project workshops as well as national and international scientific meetings. Graduate students are being trained in modern advanced methodologies in chemistry and microbiology. There is an ongoing assessment module to document education and training outcomes.Up to now, the two mainly accepted mechanisms of mortality in bacterial populations are heterotrophic protist grazing and viral infection. Increasingly, it has become evident that an understudied group of predatory bacteria, BALOs, can also contribute to bacterial mortality. Yet, the mechanisms underlying the dynamics of BALO-prey interactions are poorly understood, as are the interactions among the micropredators, BALOs, protists and bacterial viruses. Ultimately, these processes may have contrasting influences on the structure and functioning of the microbial loop, including impacting higher trophic levels and biogeochemical cycles. The investigators hypothesize that environmental factors significantly influence how mortality in bacterial populations is partitioned among the micropredators. To test this hypothesis researchers are (1) investigating the interactions amongst the micropredators, (2) examining the molecular-level composition and dynamics of dissolved organic matter as the result of the different mortality processes by the NMR/ FT-ICR mass spectrometry (MS) hybrid approach, and (3) modeling these tri-trophic dynamics. Intellectual Merit: Results from this research will define a new mechanistic understanding of mortality dynamics that influence the microbial loop and oceanic biogeochemical cycles.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

微生物是地球上最丰富的生物体，在环境中发挥着重要的降解作用，循环营养物质。太多或太少的细菌可能会破坏敏感的生态平衡和环境过程的正常运作，如碳，氮和磷循环。任何特定环境中细菌种群的丰度都受到各种生物、化学和物理机制的控制。在这些生物制剂中，有细菌的微观捕食者。其中研究最多的是原生生物，感染细菌的病毒，以及统称为蛭弧菌和类似生物（BALO）的一组细菌。 这些微型捕食者捕食某些细菌，以获得复制所需的营养或其他细胞物质。在这个过程中，被捕食细菌的细胞产物被释放到环境中，并被其他微生物用作营养物质。虽然在自然界中，微型捕食者共同出现，并可能相互作用，但大多数实验研究都是单独调查它们的活动，而不是集体调查。因此，人们对它们在控制细菌种群和营养物质循环方面的集体作用知之甚少。拟议研究的目标是通过在模拟自然条件下代表一系列温度，盐度和猎物丰富度的集体调查所有三个群体来解决这一知识差距。该项目在两所历史上黑人大学（HBCUs）进行，这些大学在培训和指导科学领域代表性不足的学生和博士后方面有着良好的记录。 该项目通过为本科生和研究生以及早期职业科学家提供独特而有意义的教育和研究培训经验，使多达100名学生受益。 具体活动包括科学写作课程和在年度项目讲习班以及国家和国际科学会议上介绍成果。 研究生正在接受化学和微生物学现代先进方法的培训。 到目前为止，细菌种群死亡的两个主要公认机制是异养原生生物放牧和病毒感染。越来越多的证据表明，一组未充分研究的捕食性细菌BALO也可能导致细菌死亡。然而，BALO-猎物相互作用的动力学机制知之甚少，因为是微捕食者，BALO，原生生物和细菌病毒之间的相互作用。最终，这些过程可能会对微生物循环的结构和功能产生相反的影响，包括影响更高的营养水平和生物地球化学循环。研究人员假设，环境因素显着影响细菌种群的死亡率如何在微型捕食者之间分配。为了验证这一假设，研究人员正在（1）调查微型捕食者之间的相互作用，（2）通过NMR/ FT-ICR质谱（MS）混合方法检查溶解有机物的分子水平组成和动态，作为不同死亡过程的结果，以及（3）模拟这些三营养动态。智力优势：这项研究的结果将定义一个新的机制理解的死亡率动态，影响微生物循环和海洋生物地球化学cycles.This奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。